LeetCode Valid Parentheses

Given a string containing just the characters

'('

,

')'

,

'{'

,

'}'

,

'['

and

']'

,
determine if the input string is valid.

The brackets must close in the correct order,

"()"

and

"()[]{}"

are
all valid but

"(]"

and

"([)]"

are
not.
题意：括号匹配问题。
思路：利用栈来处理，判断右括号的情况

class Solution {
public:
    bool isValid(string s) {
        stack<char> st;

        for (int i = 0; i < s.size(); i++) {
            if (s[i] == ')' || s[i] == ']' || s[i] == '}') {
                if (st.empty())
                    return false;
                else {
                    char tmp = st.top();
                    st.pop();
                    if ((tmp == '(' && s[i] != ')') || (tmp == '[' && s[i] != ']') || (tmp == '{' && s[i] != '}'))
                        return false;

                }
            } else st.push(s[i]);
        }

        if (!st.empty())
            return false;
        return true;
    }
};